Field of the Invention
The present invention relates to a bearing structure used in a planetary reduction gear or the like provided on a traveling unit, a swing unit, or the like of a construction machine, for example.
Description of Related Art
In a planetary gear supporting portion of a planetary reduction gear, as shown in FIGS. 8A and 8B, for example, an outer-ring-equivalent component 2 which is a planetary gear is rotatably supported via a bearing 3 by a shaft 1 provided on a fixed member 7 which is a carrier. As the bearing 3, for example, a retained roller assembly composed of a rolling element 5 such as a cylindrical roller and a retainer 6 is used. In order to receive a thrust load, a thrust washer 4 movable in the axial direction is often provided between the bearing 3 and the fixed member 7 as shown in the figures.
In this type of planetary gear supporting portion, there are cases where an oil hole for lubrication (not shown) is provided in a non-loaded area of a rolling element raceway surface 1a of the shaft 1, and oil is injected from the oil hole to the inside of the bearing 3 to forcibly lubricate the bearing 3. In this case, for example, in a bearing structure described in Patent Document 1, the space inside a pocket of the retainer is increased by, for example, reducing the size of claws that prevent the roller from dropping from the pocket, the claws being projecting from a radially inner end and a radially outer end of a surface that faces the pocket and is along the axial direction toward the inside of the pocket. Thus, running of the oil is enhanced to improve the lubricity. Further, as described in Patent Document 1 and Patent Document 2, an inner diameter surface of the retainer is tapered such that the inner diameter thereof increases outward in the axial direction, thereby to allow the oil to easily enter a gap between the shaft and the retainer. Thus, the lubricity at the inner diameter side of the retainer is improved.